Apparatus for casting metal



Dec. 23, 1958 A. c. DUNN 2,865,068

APPARATUS FOR CASTING METAL Filed Oct. 18, 1954 3 Sheets-Sheet 1 45 4 Th 5 I .l i 48 l I I 22 b 32 4/ 36 44 1 26 20 3 24 g 25 4 19 F/GZ W3 '4l3 J6 /7 :I: n I I -4 f L; Q IO n:

I l 4 Hp 9-1 ,8; 4 4* 1 4 2 41 W f FIG. 4 28 INVENTOR: ANDREW C. DUNNDec. 23, 1958 A. c. DUNN 2,865,068

APPARATUS FOR CASTING METAL Filed 001:. 18, 1954 3 Sheets-Sheet 2INVENTOR. ANDRE W C. DUNN Dec. 23, 1958 AL CKDUNN APPARATUS FOR CASTINGMETAL 3 Sheets-Sheet 3 Filed Oct. 18. 1954 FIG. /2

FIG/4 FIG /5 INVENTOR. AND/PE W C. DUNN ATT'Y APPARATUS. FOR CASTINGMETAL Andrew C. Dunn, Chicago, Ill.

Application October 18, 1954, Serial No. 462,701

Claims. (Cl. 22-69) This invention relates to the casting of metals andmore particularly to the casting of metals under pressure and undernon-oxidizing conditions.

This application is a continuation-in-part ofmy application Serial No.159,780 filed May 3, 1950, now abandoned, for Method of and Apparatusfor Casting Metal.

This invention relates to the production of improved casting, first bydegassing of molten metals by percolat-v ing inert or other gassesthrough the melt and by adsorption and absorption of the impuritiesbefore the molten metal is put into the mold.

As the speed of aircraft ha been increased in the last few years, it hasbecome more and more of a need to find a way to produce aircraftcastings free from gas, oxides and porosity, thereby providing higherphysical properties.

There have been many attempts to meet aircraft requirements but eachdevelopment and invention hasbeen.

directed toward a single problem in the casting cycle rather than asolution of the cumulative need. This has been like locking one barndoor and leaving two others open.

There have been many attempts to degasify the melt in the foundry forsand casting, permanent molds and die castings. This has been done byinjecting underneath the surface and near the bottom of the pot, gases.such as chlorine, nitrogen or other substances such as powdereddeoxidizers. Battelle Memorial Institute have shown the importance ofthe uses of these gases and materials for removing impurities from themelt by injecting the gases through the bottom ofthe melting pot whichis diflicult and expensive plus the fact that the gas takes the shortestpath to the surface and diffuses through only a part of the molten metalin the pot.

Other inventors including F. T. Kitchen in his Patent No. 969,539 ofSeptember 6, 1910, have put their minds to the feeding of the moltenmetal into the moldby applying pressure within an enclosed melting potbut they:

did not develop in their method a workablevalve that would give themcontinuous production. to overcome this valve problem, Smith Patent2,181,157 of November 28. 1939, feeds the molten metal into the moldthrough ribbon-like openings under high pressure. This sprayed themolten metal into the die cavity under the sprayed condition, oxideswere formed which froze within the casting, thereby reducing thephysical property values. openings Within the mold, the material ofthemold surrounding these openings becomes heated and time. was requiredbefore pressure could be applied to the material within the mold as theheated portions aroundth'e ribbonlike openings do not permit the metalWithin to freeze quickly causing advance solidification in parts of themold before pressure can be applied which means if pressure is put onthe molten metal within the mold before the metal filling theribbon-like openings-is frozen, the pressure will force the molten metalwithin the mold through these feed openings, the pressure then is lost.

In attempting By forcing the metal through the ribbon-like.

nited States Patent C) 2,8653% Patented Dec. 23, 1%58 ice Anotherinventor, Gerdien, in Patent 1,514,151 of November 4, 1924, attempted tomake ingots by filling the mold by vacuum with a ball valve which wasuncontrolled and when in operation, the ball would rise and permit muchof the material within the mold to return to the melting pot. Thisresulted in porosity or a pipe being formed above and below the ball inthe center of the ingot as there is a shrinkage of 57% of the metal asit changes from liquid to solid and the side walls and top of the ingotwould'be first to freeze. In this invention, the inventor made aone-piece mold instead of a split mold or a mold to carry a core.

In the present improved method of casting, I have overcome thediificulty of the prior art by making improvements in what used to becalled the different divisions of a casting unit and have built theminto a casting cycle which produces castings free from gases, oxides, orporosity, with higher physical properties at normal and hightemperatures than heretofore produced. These better results are attainedbecause of the predetermined travel and the automatic closing of theapplicants valve which happens before solidification starting in thevalve zone, thereby eliminating porosity or the formation of a pipewhich is caused by the material within the mold returning to the meltingpot; by progressive cooling of the material with the mold; by removingthe gases, such as oxygen or nitrogen by percolating a non-oxidizing gasdown through the feed pipe openings and rising through the molten metalwithin the pot, and the absorption of gases from the metal as it isagain forced through the many openings of the feed pipe from which itenters and fills the mold.

Numerous objects and advantages will appear from the followingdescription when it is read in conjunction with the accompanyingdrawings in which:

Figure 1 is a view of a pressure casting apparatus associated with amelting pot of the present invention, certain parts of the mold, themeltingpot and the furnace being shown in section.

Figure 2 is a sectional view of a modified construction, in which thecore pressurizing means of Fig. 1 is projected with cooling means;

Figures 3, 4 and 5 show different rotated positions of a valve plug asused in connection with a control valve;

Figure 5a shows a sectional View of a pressure or vacuum feed pipevalve;

Figure 6 is an elevation of one section of a casting mold arranged forbottom filling, and having a control gate with portions in sectionembodying the present invention;

Figure 7 is a fragmentary sectional view, showing a modification of thestructure of Figure 6 wherein the control-gate has a lateral metal sprueconnection for side feeding;

Figure 8 is an enlarged detail sectional View of the control-gatestructure as taken on line 88 of Figure 6.

Figure 9 is a fragmentary enlarged section of a modified form of thecheck valve structure of Fig. 1 to control the flow of molten metal fromthe melting pot to the mold chamber.

Figure 10 is a perspective view of a temperature indicator having amovable pointer for indicating selective points from which thetemperature is being read.

Figure 11 is a fragmentary sectional view of the connection of acontrolling valve into a single feeding tube;

Figure 12 is a sectional view taken approximately on the line 12-12 ofFigure 6 and illustrates a plurality of thermostatic terminals for usein connection with an indicator as shown in Fig. 10 to measure therespective temperatures adjacent a casting as it is being made.

Figure 13 is a sectional view on the line 13--l3of Fig. 1 showing across section of the metal delivery tube with straight and spiralopenings therethrough.

Figures 14 and 15 show a single cord and a spirally wrapped cord or wireto produce the straight and spiral openings respectively in the deliverytube; and

Figure 16 is a view of the lower end of the delivery tube as shown inFig. 1.

When metal having a normal amount of included gases which surround theboundaries of the molecules, is subjected to increased temperatures, thegases are the first to expand which lowers the physical properties ofthe metal more rapidly than normal as the temperature is increased andthereby lowers their working load safety factor.

In this cycle (1), first degassify and purify the metal; (2) then feedfeed molten metal into the mold rapidly without turbulence, its surfacebeing protected by an inert gas; (3) apply pressure to the metal withinthe mold immediately upon the mold being filled; (4) maintain pressureduring the cooling cycle, the casting being cooled progressively fromthe part most remote from the feeding sprues and as solidification takesplace remote from the feeding sprue; it thereby eliminates porosity, pinor blow holes; (5) further purifying the molten metal as it is fed tothe mold by adding absorption or catalytic elements into the feed tubeunit; (6) make cored castings where the core is supplied internally withgas pressure to prevent it from yielding when the molten casting is putunder pressure; and (7) make a cored casting, supplying a coolingelement to the core, causing the casting first to solidify internallyand cool progressively to the outer walls.

The present application is a companion application to my copending moldapplication, Serial No. 159,113, filed April 29, 1950, and the moldshown therein is that used in the casting operation of the presentapplication.

Referring now more particularly to the drawings, a furnace 10 has a heatinsulating lining 11, the furnace is closed by a cover 12 provided witha sealing gasket 13 and the cover is secured in position by fasteningmeans such as bolts 14. At its top, the furnace has a peripheral outsideflange 15 which cooperates with the cover 12 and has an inner flange 16offset inwardly in the furnace and supporting the flange 17 of a meltingpot 18 which extends downwardly into the furnace 10 and has ahemispherical bottom as shown. The melting pot has an inclined takeoffconnection 19 extending through the cover and sealed at this outer endby a screw cap 2001 thus providing means for the filling of the pot withmetal to be processed.

It should be understood that with molten metal in the pot 18, it isnecessary to provide heating means for maintaining the metal in a moltencondition. While no heating means is shown, it will be obvious that thefurnace 10 may contain electrical heating means disposed beneath andaround the pot, or some other heating means may be employed.

Depending within the pot 18 is a metal delivery tube 27 which has anupper reduced portion 26 extending adjustably through the cover 12 andheld at any desired elevation in the pot 18 by threaded glands and 24surrounding the reduced portion and secured in the cover. At the upperend of the tube is a hemispherical portion 23. Extending longitudinallythrough the tube 27 are a plurality of small bores 20 and also a numberof spiral bores 21 outside of the small bores. These bores feed into acommon chamber 22 and extend from a common chamber 79 at the bottomfilled with coarsely ground carbon or other materials 80 which will actto absorb or filter out coarser impurities. At the bottom of thischamber is a perforated plate 78 threaded into the end of the tube 27 toclose the chamber and to retain the filter material 80 in the chamber.

The feed delivery tube is preferably constructed of carbon, lamp blackand other catalysts or absorbing materials which have a catalysticaction in drawing out and absorbing gases from the metal. When the metalis forced through a large portion of the length of the multitude ofsmall tubes, the pure metals run freely, and foreign materials arepushed to the walls of the small tubes where they are adsorbed orabsorbed.

The gases are first adsorbed and then penetrate into the carbonmaterials of the feed tube by capillary action. In some cases, theporous matter 80 above the plate 78 may be dispensed with and thecapillary tubes within the delivery tube 27 may be increased in length.

When it is desired to further strengthen the cast metals, boron,tungsten and other metals may be added to the material in the deliverytube in coarsely ground particles, parts of which will project into themany passages where they will be consumed by the metal as alloyingagents or will act as catalysts. There are many other metals ormaterials that may be used for this purpose which are known to menskilled in the art and which may be developed by trial.

To produce the passageways in the delivery tube, they may be drilled orbored in the delivery tube, or single wires or fibers 82 as shown inFig. 14 or spirally wound wires or fibers 83 and 84 as shown in Fig. 15may be placed in the mold when the delivery tube 27 is being cast. Whenthis tube is scintered, the wires will melt and flow out and the fiberswill be shrunk forming additional carbon leaving the openings 20 and 21for the passage of molten material therethrough. The spirally woundfiber of Fig. 15 provides an additional surface within the passages formore adsorption or catalytic action. The passages may also be formed byother materials such as the material to be treated or other metals whichwill melt before the melting of the carbon or alloys of which thedelivery tube is composed.

The upper hemispherical end 23 of the delivery tube engages thehemispherical sprue 32 formed of the two halves 33 and 34 as shown insection in Fig. 8. Any conventional structure may be employed foropening and closing the die, but as shown, die part 33 is fixed whereasdie part 34 is movable on guides 35 and 36 when actuated through acontrol rod 37. A source of high pressure gas (preferably a gas inertwith respect to hot molten metal), is supplied through a pipe 38 tosupply lines 39 and 40 controlled by valves 41 and 42 respectively. Thepipe line 39 leads to a metal collecting cavity 56 which may also be alarge portion of the castings, to which it may apply high pressure,whereas the pipe line 40 leads to the interior bore 22 of the tube 27through a pipe 43, and also to a mold cavity through a take-off pipeconnection 44, both pipes controlled through a four-way control valve30. This four-way valve 30 permits pressure to be admitted to the moldcavity 45 through the pipe 44 and/ or to the ante-chamber at the top ofthe bore 22 through the pipe line 43.

As represented in Figs. 3, 4 and 5, this valve has a connection 29 tothe atmosphere and two valve passages 28 and 27 in the valve itself. Thevalve may be turned as shown in Fig. 3 to admit pressure by passage 27from the pipe 40 through the valve and pipe 43 to the antechamber at thetop of the tube 27; it may be turned as shown in Fig. 4 connecting thepassage 28 to admit atmospheric pressure from the atmospheric inlet 29to the pipe 43 as shown in Fig. 4; and it may be turned to connect thepipes 40 and 44 by the passage 28 as shown in Fig. 5.

The pot 18 is also provided with a gas supply pipe 46 under the controlof a valve 47 for supplying gas under low pressure to the pot for metalejection when the mold is to be filled under low pressure. This valvemay be turned as shown in Fig. 5a to exhaust or relieve the pressurefrom within the melting pot.

The gate for the mold is closed by a check valve comprising a ball 48(Fig. 6) in a chamber 49 having a seat 50 closed by the ball. The seat50 is a reduced extremity of a rod 50A which extends through the moldpart with the seat projecting within the chamber 49 so that the seatremains in place when the mold parts are separated and a ball 48embedded in and is removed with a casting. A rod 51 extends across thetop of the chamber for confining the ball within the chamber 49 formedbetween the seat 50 and the rod 51. The gate for the moldis closed bythe ball 48 which permits the flow of metal into the mold when underpressure, but prevents retrograde movement when the pressure within thepot is relieved. When the mold has been filled and the metal solidifiedtherein, the ball 48 will be embedded in the metal in the sprue and willbe removed therewith when the sprue, gate and casting are removed fromthe mold. The rod 51 is an- 'chored in the mold part 34 and the castingis slipped or'f from it when the casting is removed from the mold.

Before each successive filling of the mold, a new ball 48 will be placedon its seat and this provides a convenient and inexpensive means forcontrolling the one-way flow of molten metal into the mold.

While the check valve has been illustrated as c-ompris ing a seat and aball, this form of the invention resides in the use of a valve having aremovable portion which becomes embedded in the cast material and .isreplaced before each casting operation. Various types of check valvesmay be used in this manner and also another common form has beenillustrated in Fig. 9.

The arrangement of Fig. 2. as hereinafter described is similar to thatof Fig. 1 except that one end of a coolant line 60 is connected to theinterior of the cavity 45 for internal cooling of the casting.

Referring now to Fig. 6, one of the mold sections of Fig. 1 isillustrated, it being understood that the other mold section is similarthereto. Although the mold sections may take various forms ofconstruction, it is desired to illustrate the present invention with thesection made bythe'method of my copending application referred to above.The 'mold comprises solid blocks of sintered powderedmaterial having aplurality of cavities shaped in the faces thereof. At the opposite sideof the center of the blocks are article forming cavities 52 connected bythe branches of the gate cavity which lead from the sprue 32 Thedome-shaped cavity of the sprue 32 fits thetop of the tube 27 as shownin Fig. 1 so that metal may enter from the pot 18 through the valve 48and then up through the gate branches into the article cavities as wellas into a reservoir cavity 56 to provide a supply of molten metal forthe purposes described hereinafter. Extending from the reservoir intothe outer wall of the mold, a half cylindrical cavity is provided forreceiving a plunger 57 extending through the top of the mold.

If it is desired to provide a hollow casting, a core 58 is disposed inthe article cavity as shown in Fig. 6. If this core is made of porousmaterial, a feed pipe 59 has its end embedded in the core and suitablepasages are provided to enable fluid under pressure in the pipe 59 tofiow into the pores of the core and build up and sustain pressure in thecore. The pressure in the core enables it to withstand compactingpressure of the metal in the mold. After the mold has been filled andthe metal has been solidified, this sustaining pressure is relieved andthe casting is allowed to contractas in normal casting operations. Pipes69 leading into and from the cores provide a circulating passage withinthe core when it is desired either to cool or to heat the core byfluidpassing through the pipes.

As illustrated in Fig. 6, the mold may be made of sintered powder ofdifferent heat conductivity, the powder forming the walls of the articlecavities opposite that of the gate may be of high conductivity such ascopper while the powder forming the walls of the gate is of lowconductivity such as iron or clay. Extending from the article cavitiesto the outer walls of the mold are vents 61 of the usual ribbon-likeform to permit the escape of air or gas when the mold is being filled.The cavity 56 receives molten metal in excess of that necessary to fillthe cavities forthe articles 52 and charged into the mold through thesprue 32 and gate controlledby the balli48. The plunger 57 is providedfor the mechanical application of pressure to the molten metal which hasbeen charged into the mold cavities. The gate valve provides aneflicient and inexpensive and readily replaceable check-valve whichseats by gravity and prevents the back-flow of molten metal. from themold into the ante-chamber and into the tube 27 or its equivalent whenthe actuating pressure is removed andwhen pressure is applied to themetal in the reservoir 56 throughthe plunger 57. The upward travel ofthe ball is limited by the cross pin 51.

In Fig. 7, the same elements as shown and described with respect to.Fig.6 are included except that thesprue 32 is arranged for side filling.

For the purposes of clarification, the detailed operation of theapparatus shown in Fig. 1 is as follows: With the mold part 34 in theposition shown, and the ball 48 on its seat, metal such as aluminum willbe supplied to the pot 18 through the connection 19'and the closure 20placed in closed position. This metal will flow around the delivery tube27 and upwardly into the bores 20 and 21 until it finds a level in thebores substantially equal to that of the level of the metal in the pot18.

Gas under low pressure is now supplied through the pipe 46 which willforce the molten metal upwardly through the delivery tube 27 into theante-chamber 22 and unseating the ball 48,'passing into the gate andfrom thence into thearticle cavities 52 and to the reservoir 56. Whenthe article cavities and reservoir are filled, high pressure will beapplied from supply line 39 to the reservoir cavity 56 and if applicableto the cores 45 through pipe connection 44 by manipulation of valves 42and 30," the valve 30 being positioned at this time as shown in Fig. 5,the pipe 43 being closed to pressure from the valve 30 at this time.

Immediately upon application of pressure, the entire amount of metalwithin the mold including that in the article cavities, the reservoirand the gate will be subjected to high pressure and the mold check valve48 will immediately seat against the low pressure in the tube 27. Theclosing of the valve serves to trap the pressure in the mold allowingthe pressure applied to the article cavities to build up.

It is noted that the sizable stream of molten metal under pressure atthe top of the pot 18 flows without turbulence through the bores 20 and21 of the tube 27 into the gate, and thence to the article cavities.Con-V tamination from the oxidizing influence of air in the mold isprevented and this feature constitutes an improvement over prior artwhen fed ribbons of metal, or utilize an atomizing efiect and thecorresponding turbulence of a pressure spray. The reservoir 56 presentsa ready supply of molten metal under pressure for feeding into thearticle cavities as the metal in the cavities solidifies and shrinks.The metal fed from the reservoir progressively fills the spaces causedby shrinkage.

When starting the unit, the metal is fed into the mold, the mold isfilled by using the delivery tube 27 and re filling the mold a number oftimes and each time remov ing imperfect starting castings, in a wellknown manner, to bring the mold up to the proper working temperature. Assoon as the mold is filled, the valve 36 for controlling a source ofinert refining gas under pressure is opened as shown in Fig. 3 to injectthe refining gas into the delivery tubes. The gas forces the moltenmetal back into the pot. The valve may be leftopen for a predeterminedlength of time until the proper amount or gas is applied for returningthe metal to the pot and refining it by removing the gases and otherimpurities. The inert refining gas is forced to the bottom of the potwhere it mushrooms outwardly and then rises, purging the impurities awayfrom the mouth of the feeding tubes.

When an inert refining gas is forced downwardly through the passages 20and 21, a portion of the im purities, such as gas and oxides, are Washedout with it leaving the tubes filled with inert gas and some impurities,solid or gases adhering to the tube walls. When the molten metal againenters the tubes, the refining gas is forced upward ahead of the metalinto the mold and out through the mold vents, as hereafter explained.This gas fills the mold and purges the air from the mold leaving thecomplete mold cavity full of refining gas at low and controlledpressure. As the gas is purged out of the mold by the incoming moltenmetal, the walls remain coated with inert gas held thereon by adhesion,and preventing the molten metal from oxygen Or other gas absorption.

The pressure behind the molten metal fills the mold and forces therefining gas out through the vents, the refining gas always covering andprotecting the molten metal.

A special feature of this invention is that after each casting injectionvalve 47 is opened to let the pressure out of the pot, and then,refining gas is purged through the tubes 20 and 21 of the delivery tube27 forcing-the metal downwardly into the pot, mushrooming or spreadingthe refining gas at the bottom of the pot at the same time refining themetal. The gas follows down through the metal and rises all around thedelivery tube 27, thereby refining the molten metal in the pot for thenext injection. This cycle goes on, the metal to be cast becomes cleanerand more refined.

The delivery tube 27 may be of any suitable length; it may be insulatedor heated to any desired temperature, and a portion may be above oroutside of the melting pot. It may be straight as shown, coiled withinthe pot or a portion extended on the outside of the pot. The refininggas may be recovered, refined, and rinsed when desired, or it may beflushed out. With this cycling, as described, the resulting castingswill be clean and dense, and thereby have higher physical propertiesthan other currently made castings at both normal or high temperaturesand they will have a higher marketing value.

These castings may be used where high physical properties are needed, asin aircraft, as pre-form shapes as used in my Forging Method Patent No.2,494,935 of January 17, 1950, as slabs or ingots for rolling orprefabrication, or as castings to be machined.

This method and operation is of particular advantage when the mold isconstructed of conducting material affording differential cooling of thecast parts. With this type of mold, the high conducting portion of themold surrounding the article opposite the feed gates, and graduating tothe low conducting portion of the mold surrounding the cavity adjacentthe gate thereby promote progressive solidification of the castings. Themetal under high pressure solidifies in a thin layer against the cavitywall, any tendency to separate from the wall being prevented by the highpressure supply of molten metal. An inner thin layer is solidifiedagainst the first layer, and thus, layer by layer the solidificationtakes place, each layer being forced to the shape of the article cavityuntil the metal in the cavity is entirely solidified. This layer bylayer solidification is by way of illustration only, as distinct layersare not presented. However, this serves to emphasize the progressivesolidification from the far side of the article cavity to the sideadjacent the gate. This increases the density of the casting and forcesit to h ld to the dimensions of the article cavities. When castings withhigh physical properties are not necessary, supply line 39, pressure onthe cavity 56 or by plunger 57 need not be used.

After a casting operation has been completed and the metal in the moldhas solidified and cooled to a predetermined temperature, the pressuresare removed, the mold is opened and the castings and the metal of thegate and sprue including the ball 48 are removed. Another ball isinserted, the mold halves are closed and the apparatus is ready foranother casting operation. The rod 51 and the interior mold parts arecoated by spraying or washing with a lubricant or parting material toprevent them from adhering to the cast material, as commonly done incasting production.

Immediately after the application of high pressure through the supplyline 39, or by plunger 57, the upper portion of the melting pot issubjected to atmospheric pressure by turning the valve 47 to atmosphereas represented by the position in Fig. 5a at the same time the valve 30is opened to line pressure as shown in Fig. 3 or open to atmosphere,Fig. 4, whereupon the metal sinks in the tube 27 to the level of themetal in the pot. This prevents freezing or solidification of the metalin the upper portion of the tube 27 adjacent to the sprue 33 andtherefore continuous subsequent casting operations are possible. It isclear that by turning the valve 30 to the atmosphere and opening thevalve 47 to atmosphere (Fig. 5a), the vacuum caused by the column ofmolten metal in tube 27 is broken, thereby allowing the metal in thetube to sink to the level of the molten metal in the pot. When refininggas is used as shown in Fig. 3, the molten metal that fills tube 27 isforced out the bottom opening of tube 27 back into the pot.

The admission of pressure through the pipe 44 into the core of thecasting prevents the collapse of core when it is subject to the pressureof the molten metal which in turn, is subject to the pressure in thesupply line 39 or plunger rod 57. It may be desirable to cool the coreat about the time pressure is applied by the plunger 57, to provideprogressive solidification of the metal in the cavity. In thisoperation, the conductivity of the mold is so designed as to promoteprogressive solidification around the core line. The core 45 may becooled by fluid applied through the coolant line 53.

To make a tight flexible joint between the tube 27 and the cover 12 ofthe pot, an expansible Sylphon sleeve as shown in Fig. 11 may beattached at its lower end to a ring 61 secured to the top of the coversurrounding the tube 27 by fastening bolts 62. The top of the Sylphon issecured to the tube 27 by a split clamping ring 63. The valve 30 may beconnected through the Sylphon to the central bore 27 of the tube by thepipe 43 which has a plug 64 at its end with minute holes therein so thatthe molten metal does not enter the pipe 43 nor clog it when the metalfills tube 27.

In order to observe the temperatures present at various parts of themold, a plurality of thermocouple terminals 65, 66 and 67 are variouslydisposed in one of the mold sections 34 as shown in Fig. 12 with respectto the cavity 56 and at different points along an article forming cavity52 and these thermocouples are connected to a pyrometer 68 as shown inFig. 10 at the points marked 1, 2 and 3 thereof respectively. Differentcontacts are made with either of the points 1, 2 and 3 in the pyrometeras indicated by a rotatably movable pointer 70 so that the pyrometerreading for any one of the locations of the thermocouple terminals canbe obtained and observed on a scale 69 of the pyrometer. This willenable an operator to observe what is taking place at the various pointswithin the mold at any desired time, thereby enabling one to obtain thebest results in mold cooling in order to produce uniform castings.

In Fig. 9, a conical valve 71 is shown seated on a corresponding valveseat 72 instead of the ball valve 48. A chamber 73 is provided in asprue 33B over the top of the valve allowing it to rise therein whenmolten metal rises in the bores 22 ahead of the delivery tube 27. Tolimit the upward raising movement of the valve 71, the valve has adepending stem 74 in which is a longitudinal slot 75 engaged by a crosspin 76 which limits the rising movement of the valve from its seat. Thisvalve would have the same operation as the ball valve but is not removedwith the casting or feed sprue. The sprue and casting are removed fromthe mold as previously set forth without the value.

The present invention produces castings with smooth 9, surfacesandsharp-definition at thecorners and edges, and castings held to closedimensional tolerances. The physical properties are more, satisfactory,and consequently; represent a great advance over the products made bythe die casting or sandcasting processes of the prior art. The singlefeature of supplying a sizable steady stream of molten metal to thearticle cavity which prevents the internal structure of the metal fromcoming in contact with the air produces a more homogeneous internalstructure in the cast article. This is particularly significant whenhighly oxidizable metals such as aluminum are cast, as the turbulenceaccompanying feed in the prior methods tends to separate the metalintoparticles which are oxidized and are frozen in the casting when itcools.

The refining method here described removes many impurities. The mostinjurious are the gases such as hydrogen, oxygen and other includedgases which are removed by inert gas delivered to the molten materialdownwardly through the delivery tube 27 and then rising through themolten material."

The method of supplying refining gases under the surface of the moltenmetal has been used before this, but supplying it into the delivery tubeat the top thereof and through the tubes to the bottom of the meltingpot where the gas mushrooms and spreads throughout the entire melt whichcan be refined after the making of each casting, is believed to be new.

It is also considered novel to use refining material surrounding thedelivery tubes which adsorbs and absorbs impurities between each castingoperation as herein described.

In this method, preferably the material being cast is not only refinedby the inert gases, but the feed pipe is made by a refining or catalyticagent that further refines the metal as it progresses on its way to themold. The metal remaining within the delivery tube at the time the moldis filled is again refined as it is returned to the furnace.

When refining gases are injected beneath the molten material, the gasexpands into bubbles which form partial vacuums into which foreignmatters are drawn and they are carried to the top of the melt where theyunite with the flux at the surface of the melt and are removed from timeto time when the removable cover is ofi for refill.

The small openings of the delivery tube also act as filters for theincluded substances such as oxides and other foreign matters such asiron are acted upon by the catalyst of the feed pipe and are convertedto iron oxide which is trapped.

When the delivery tube is saturated with impurities such as .solidsfiltered out, it may be bored to renew the feed tubes, and whensaturated with gases, it may be rehabilitated by heating it to thetemperature that will drive the gases out of the material of the feedpipe.

While the technique set forth above has been described specifically asapplied to the casting of metals, it is to be understood that theinvention is also applicable to the casting of other materials such asplastics, ceramics and the like. Accordingly the above description is tobe read and interpreted broadly, and not limited to the casting ofmetals.

It will be understood that only a few of the modifications of thisinvention have been illustrated, and that various changes andmodifications will be possible within the scope of the appended claims,without departing from the spirit and scope of the invention.

Having thus described the invention, what is claimed is:

1. A casting mold comprising a plurality of mold sections having aninlet associated therewith and a check valve in said inlet, to permitflow of liquid into said mold under pressure but to prevent reverseflow, said valve including a controlling member and a fixed seat forminga part of said inlet and a removable portion which becomes embedded inthe molded material when 10 themold is filled, the division of 'saidmoldinto a plurality of sections passes through and divides saidinlet,exposing said 'removableportion for removal with the molded material.

2. A casting mold comprising a plurality of sections forming a ventedcavity, a sprue for said mold, check valve means having a controlledmovable part carried by molten metal in said sprue for permitting onlyone-way flow of molten material through said sprue, an oversupply ofmolten material in communication with said cavity, and pressure applyingmeans associated with said supply for applying pressure to the moltenmaterial in said cavity, to thereby subject the casting to highdensifying pressure while it is cooling.

3. A casting mold comprising a plurality of sections forming a cavity, acore in said cavity, check valve means having a controlled movable partcarried by molten metal for regulating the supply of moltenmetalto saidcavity, pressure supply means for applying densifying pressuretothe'molten metal in the cavity, and pressure supply means for applyingsubstantially equal pressure to the interior of said core.

4. Pressure casing apparatus comprising a pot of molten metal, a moldincluding article cavities and a surplus material section, and a gateconnecting said cavities and section, said gate including a controlledcheck valve admitting metal to said mold but automatically closing saidvalve, a delivery tube depending in said pot and connecting said potwith said mold, means for applying pressure to said pot to deliver metalfrom said pot to said mold through said check valve, and means forsubjecting the metal in said section to high pressure through theconnecting gate to subject the metal in said article cavities to saidhigh pressure.

5. The apparatus as specified in claim 2, wherein said movable part isadapted to close said valve, the movable part remaining within thecasting, and a seat through which the metal moves in filling the mold.

6. The apparatus as described in claim 4, wherein the metal forming thearticle cavity of the mold is of relatively high heat conductivity inthe region of the cavity opposite the feed gate entrance theretodecreasing gradually to the feed gate side thereof.

7. A mold comprising an article cavity and a gate comprising an entrancein and into said mold, an entrance to said article cavity, a reservoirconnected to said gate intermediate said entrances, means for applyingpressure to the metal in said reservoir, and a check valve having afixed seat and a controlled movable part at said entrance to said mold.

8. A mold as described in claim 7 wherein said mold is formed insections for ready removal of the cast article and said check valveincludes a controlled movable valve portion and a fixed seat in saidsectional construction for holding the movable valve portion as part ofthe solidified casting.

9. The mold of claim 7 including a check valve with a fixed bar forlimiting the movement of said movable part in said mold entrance andmeans for subjecting the material in said mold to high pressure, saidcheck valve preventing the metal leaving said mold under the influenceof said pressure being applied immediately upon filling the mold.

10. A casting mold comprising a mold having an article forming cavityand an entrance conduit and gate for receiving molten material into themold and conducting it to the article cavity at the side thereof, areservoir for excess metal within said mold and communicating with saidgate, an automatic check valve at said entrance, and means for admittinga pressure force to said reservoir, said mold being formed of powderedmaterials of progressively different heat conductivity to conduct theheat from said cavity in a predetermined order to provide forprogressive solidification of the cast metal in that order.

11. In a casting apparatus, a supply receptacle, a casting mold, smallpurifying tubes for delivering molten material from the receptacle tothe mold, and means for applying an inert gas through the tubes and toreturn the molten material into the container, and to percolate the gasthrough the material in the container to further purify the material.

12. In a casting apparatus, in accordance with claim 11, the tube beingcomposed of catalytic adsorbent and absorbent materials which constitutea purifying agent for the said gas.

13. In a casting apparatus in accordance with claim 11, the tube beingcomposed of an alloy of catalytic material which acts upon the moltenmaterial which passes through the tube.

14. In a casting apparatus in accordance with claim 11, the tubecomprising a plurality of passages therethrough for the passage of gasesand molten materials in both directions.

15. In a casting apparatus in accordance with claim 11,

an expandable connection between the receptacle and the tube.

References Cited in the file of this patent UNITED STATES PATENTS721,381 McAdams Feb. 24, 1903 969,539 Kitchen Sept. 6, 1910 1,019,965Kelly Mar. 12, 1912 1,150,318 Wetherill Aug. 17, 1915 1,214,904 DoehlerFeb. 6, 1917 1,514,151 Gerdien Nov. 4, 1924 1,717,608 KadoW June 18,1929 1,895,245 Geisler Jan. 24, 1933 1,996,335 Jones et al. Apr. 2, 19352,040,165 Baldwin Mar. 12, 1936 2,181,157 Smith Nov. 28, 1939 2,268,981Ericson Jan. 6, 1942 2,281,867 Anthony May 5, 1942 2,479,364 JocelynAug. 16, 1949 2,495,276 Milton Jan. 24, 1950 2,522,046

Knowlton et a1 Sept. 12, 1950

